Recently there has been rapid development in geotechnical centrifuge modelling technology world-wide, and centrifuge testing is now commonly used for reduced-scale physical modelling of geotechnical and geo-environmental systems. In this paper, a new 400 g-ton state-of-the-art geotechnical centrifuge facility in Hong Kong is introduced and some of its unique and advanced capabilities such as in-flight bi-axial shaker and 4-axis robotic manipulator are described. This facility is dedicated to serve not only the University but also the entire geotechnical community in Hong Kong and around the world.
Due to the possible change of microseismic environment of Tainan Science and Industrial Park as the high-speed train pass through the Park in the coming future, the installation of full-time micro-vibration monitoring system will benefit to manage the seismic environment of the Park. The purpose of this paper is to present the planning, design and installation of fully automated computer-based environmental vibration monitoring system. A total of three monitoring stations were constructed in the past year. The stations are fully automated, unrest to monitor the ground vibration and to perform one-third octave band analysis, and display the result on the screen. From the measurement, the time domain data and frequency domain data are stored in the hard disc, respectively. From the development, the microvibration monitoring is successful and well performed in the Park.
This paper describes the researches concerning the commonly used energy transfer measurement methods for standard penetration tests. Problems of the SPT energy transfer were once of less care, and the recently growing needs on quality assurance of construction works have called more attention. A SPT energy transfer route can be subdivided into stages, and energy measurement corresponding to different stages are delineated in respect to some available methods. In order to explain the computation of measured energy, a comparison is made between the force square integration method of the current ASTM code and the force-velocity integration method of the future ASTM reviewing. A study is presented to analyze the influence of hammer shape using the calibration testing in the laboratory. Testing results of three different cylindrical hammers and a safety hammer indicate that the influence of hammer to the energy transfer is of insignificance providing the hammer drops in free-fall case. Based on the laboratory results, the paper recommends a round-headed anvil to replace the currently adopted flat-headed anvil in SPT tests to improve the energy transfer process.
Understanding of the fundamental properties of unsaturated soils requires sound understanding of the relationship between the soil suction and the water content, and the effect of matric suction on the shear strength parameters of unsaturated soils. This paper introduces the method for the measurement of the matric suction and the principle of the pleasure plate test that is commonly used to measure the relationship between the soil suction and water content. Subsequently, a triaxial apparatus is used as an example to illustrate the principle of shear strength testing and evaluation of unsaturated soils. Finally, the current application and future development of unsaturated soil mechanics on slope engineering is discussed.
Application of Time Domain Reflectometer (TDR) in geotechnical measurements is a relatively new development. It can be used to measure electrical properties of soils that are related to soil physical properties. In addition, TDR has found applications in monitoring ground water level and relative deformation in soil, rock, or structure. This paper introduces the basic principle of TDR measurements and explains the methodologies of TDR measurements in geotechnical application. The potential and future development of TDR is also discussed.
Geotextiles are human made new construction materials that have influenced the construction in the areas of geotechnical engineering, transportation engineering, environmental engineering, and hydraulic engineering, etc. Geotextiles perform seven major functions: separation, reinforcement, filtration, drainage, liquid barrier, protection, and erosion control. In the design, selected geotextile should satisfy the requirements for the applied functions and its associated contract specifications. For strength consideration, tensile strength is the most important material property for geotextile that can be evaluated by various types tensile strength tests. The most commonly utilized geotextile tensile test methods are narrow strip tensile test, grab tensile test, and wide-width tensile test. This paper discusses the scope, significance and use, conditioning, apparatus, procedure, sampling, and calculations of these test methods. The typical problem that associated with geotextile contract specification is also discussed.
The outcrops in the central and northern regions of Western Taiwan often contain poorly cemented, very weak and young rock formations. The rock sampling process is likely to damage the structure that originally existed in the rock mass. For this reason, in situ testing is a desirable alternative in characterizing the properties for soft rocks. The authors have developed a high stress pressuremeter specifically for testing in soft rocks. The new pressuremeter can sustain a maximum expansion pressure of 25 Mpa, and instrumented with 12 strain-gauged strain arms. The Lugeon test equipment typically used to conduct field permeability tests has been modified to enhance the quality of test results. The authors established a test site in Bao Shan Township of Hsin Chu County, where a series of high stress pressuremeter tests, Lugeon tests, and P-S logging tests were conducted. This paper describes details of these test equipment, procedure, interpretation of the data and their implications in the characterization of soft rocks.
There are many advantages of tunnel excavation with the tunnel boring machine (TBM), such as high penetration rate, lower disturbance, continuous operation, and less loosening of surrounding rocks. Until now two tunnels were excavated by the TBM in Taiwan. One is the Pinglin Pilot (PP) tunnel with a diameter of 4.8m and a length of 12.9km, and the other is called the Shihlin Headrace (SH) tunnel with a diameter of 4.53m and a length of 5.5km. This paper presents an evaluation system to show the relationship between the TBM performance, such as penetration rate, utilization rate as well as advance rate, and the geological conditions, I.e. rock strength, geological formation, total hardness, and rock mass rating (RMR).